The stunning turnaround in U.S. military fortunes in Iraq is now so obvious that it's getting Page One treatment and network/cable broadcast time by an American press long preoccupied with reporting this war's negatives. There are lessons here for anyone who will examine the facts in Iraq, perhaps even for Democrats in Congress and those running for president whose unchanging mantra remains "we've lost, get out now."

The evidence, building month by month since the surge in U.S. troop levels last spring and summer, is unmistakable.

Violence is down all across Iraq, in Baghdad by 75 percent. Al-Qaeda in Iraq, long the primary terrorist threat, has been routed. Thousands of Sunni insurgents who were once avowed enemies of coalition forces and the Iraqi government have switched sides. The Sunnis, appalled by the terrorists' tactics of indiscriminate mass murder, are now fighting al-Qaeda and cooperating with the Americans and with Iraq's security forces. U.S. casualties are running at two- and three-year lows.

Sectarian reconciliation, while still stalled at the national level, is taking root at the local and provincial levels. Iraqi refugees sheltering in neighboring Syria and Jordan are beginning to return to neighborhoods made livable again.

So, what do we learn from all this?

First, the troop surge so roundly denounced by those who had given up on Iraq worked. Putting five additional combat brigades (about 30,000 troops) into central Iraq, notably Baghdad and its successive belts of suburbs and satellite cities, reclaimed Iraq's capital from the car bombers and sectarian death squads.

Just as important as the additional numbers of troops was a fundamental change in U.S. military strategy and tactics. Troops were pulled out of their heavily fortified mega-bases and deployed, neighborhood by neighborhood, in local security stations together with Iraqi soldiers and police. This tangible presence provided both security and invaluable intelligence on who the terrorists were, where their arms caches were hidden and the attacks they were planning.

It produced the two indispensable ingredients of successful counterinsurgency warfare: Protection for the civilian population and actionable intelligence on the enemy.

Al-Qaeda has been run out of Baghdad and its surrounding cities, an area comprising the demographic and military center of gravity in the struggle for a stable Iraq. Providing security to a heretofore frightened and intimidated civilian population is yielding a flood of intelligence tips on the terrorists and sectarian killers. A measure of popular Iraqi support for coalition security efforts is the formation of local self-defense groups, called, prosaically, Concerned Local Citizens. In little more than the past six months, 70,000 Iraqi civilians have joined hundreds of these CLC groups to assist in protecting their own neighborhoods.

All this is evidence of a counterinsurgency campaign gaining critical mass against an increasingly discredited enemy.

The troop surge also served an additional purpose vital to stabilizing Iraq.

Sending more U.S. forces and establishing the local presence previously lacking were tangible proofs to Iraqis that the United States was committed to its mission in Iraq. The message to millions of Iraqis was that they would not be abandoned, either to a murderously ruthless terrorist enemy or to uncontrolled sectarian violence in a country that barely a year ago seemed poised on the brink of civil war.

The psychological transformation this reassurance is producing in Iraq is potentially decisive.

Without it, the Sunni sheiks and their tribes wouldn't be changing sides and casting their lot with the Americans and a Shiite-dominated Iraqi central government. Without renewed confidence in the resolution of coalition forces, tens of thousands of Iraqis wouldn't be joining the CLC groups and turning in the bombers and killers in their midst. Without a demonstration of American determination to get the job done in Iraq, the Shiite militias of Muqtada al-Sadr wouldn't be standing down and observing a truce with coalition forces.

The surge has also sent a sobering signal to Iraq's neighbors, Syria and Iran especially, that America is not running. Syria is stopping more al-Qaeda recruits at its border with Iraq and Iran appears to be scaling back its arms supply to al-Sadr's militias.

No, the war in Iraq is not over. The gains this year may not yet be irreversible. But a drawdown in U.S. combat forces in 2008 now looks feasible without conceding defeat. A war America and its Iraqi allies were losing a year ago now looks winnable, after all.

Robert J. Caldwell is editor of The San Diego Union-Tribune's Sunday Insight section and can be reached by e-mail.